Detachable connection for coupling a gas exchange valve of an internal combustion engine to an actuator

ABSTRACT

Disclosed is a simple, easy-to-produce, and reliable connection between a shaft of a gas exchange valve and an actuator. This connection is detachable and, as a result, can be connected and disconnected multiple times. It is also possible to dispose the coupling piece on the shaft of the gas exchange valve and provide circumferential grooves on the control element of the actuator  5.

PRIOR ART

The invention relates to a connection of a gas exchange valve of aninternal combustion engine to an actuator according to the preamble ofclaim 1.

In internal combustion engines whose gas exchange valves are activatedin the conventional manner by way of a camshaft, the activation motionof the camshaft is transmitted to the shaft of the gas exchange valve byway of a bucket tappet, a drag lever, or a rocker, for example, whenthis gas exchange valve is to be opened. A valve spring clamped betweenthe cylinder head and the gas exchange valve keeps the gas exchangevalve in constant contact with the bucket tappet, drag lever, or rocker.In addition, the valve spring serves to close the gas exchange valve.

In modern engine designs, gas exchange valves are no longer activated byway of a camshaft, but rather by actuators such as piezoelectricactuators, hydraulic actuators, or pneumatic actuators, for example. Inthe context of the invention, the term “actuator” is considered toinclude all regulating elements capable of performing the opening andclosing motions of a gas exchange valve, regardless of their physicaloperating principles. The actuators open and close the gas exchangevalves desmodromically, i.e., forcibly. Therefore, it is necessary toproduce a connection between the actuator and the gas exchange valvethat can reliably transmit the forces necessary for opening and closingthe gas exchange valve.

The object of the invention is to produce a simple, inexpensive, andreliable connection between the gas exchange valve and the actuator. Atthe same time, it should be possible for the connection to bedisconnected and reconnected multiple times and, at the same time, theconnection should require only minor changes to the gas exchange valveand the cylinder head of internal combustion engines that are already inseries production.

This object is attained according to the invention by a connection of agas exchange valve of an internal combustion engine to an actuator,having a shaft and a coupling piece in which at least onecircumferential groove is provided on the shaft, the coupling piece hasa bore whose diameter in the assembled state corresponds to the diameterof the shaft, the bore has at least one circumferential bead that can beconnected in a positively engaging fashion to the at least onecircumferential groove, and the coupling piece has at least onelongitudinal slit in the vicinity of the bead.

ADVANTAGES OF THE INVENTION

The connection of the gas exchange valve and actuator according to theinvention is based on a positive engagement that has the same loadingcapacity in both activation directions of the actuator (opening andclosing the gas exchange valve). Moreover, with the connection accordingto the invention, it is possible to use a conventional gas exchangevalve because the coupling of the gas exchange valve to the valve springis also provided with circumferential grooves in the vicinity of theshaft of the gas exchange valve. Another advantage of the connectionaccording to the invention lies in the fact that it has a very smallnumber of components, which simplifies production and assembly as wellas repairs. Furthermore, in the connection according to the invention,it is possible to rotate the gas exchange valve in the same manner as inconventional internal combustion engines.

In order to increase the forces that can be transmitted between theactuator and the gas exchange valve, the shaft can be provided with anumber of circumferential grooves spaced apart from one another in thelongitudinal direction. Correspondingly, the bore has a number of beadsspaced apart from one another in the longitudinal direction.

In one variant of the invention, the shaft is embodied in a cylindricalshape in the vicinity of the at least one circumferential groove and thebore is embodied in a cylindrical shape, so that the object can beattained in a particularly simple manner from a production engineeringstandpoint. As an alternative, the shaft in the vicinity of the at leastone circumferential groove and the bore can be embodied in the shape ofa truncated cone.

Other enhancements of the invention provide for embodying the at leastone circumferential groove with a semicircular, rectangular, ortrapezoidal cross-section, thus allowing an optimal variant to beselected depending on the requirements with regard to production,assembly, and the forces to be transmitted.

A securing element can be provided in order to prevent the connectionaccording to the invention from becoming detached during operation.

In another variant of the invention, the securing element is embodied asan open wire ring and the coupling piece has at least one groove on itsouter surface to accommodate the securing ring, so that the connectionis secured by sliding the wire ring into the groove.

In another embodiment of the invention, the securing element is embodiedas a nut and the coupling piece has an external thread on its outersurface, which cooperates with the nut, so that screwing the nut ontothe external thread prevents the connection according to the inventionfrom becoming detached.

In a further enhancement of the invention, the securing element can beembodied as a sleeve that can be slid over the coupling piece. It isalso possible for the sleeve and coupling piece to be pressed againsteach other in the assembled state and to thus form a force fit. In thisembodiment, which is very simple from a production engineeringstandpoint, the securing element can be effectively prevented fromcoming off the coupling piece during operation and, moreover, the factthat a specific tool is required to produce a press-fit connectionensures that only authorized garages can perform repairs to the actuatorand/or the gas exchange valve.

In order to simplify assembly, it is possible for the coupling piece tobe spread out in the vicinity of the at least one bead in relation tothe mounted state and for the coupling piece to be pressed together bythe securing element during assembly. In contrast to the exemplaryembodiments described above, the connection between the gas exchangevalve and the actuator in this variant is not embodied as a snapconnection, but rather the positive engagement is produced only when thecoupling piece is pressed together and the securing element issubsequently slid into place.

According to the invention, the shaft is part of the gas exchange valveand the coupling piece is part of the actuator. However, it is alsopossible for the coupling piece to be part of the gas exchange valve andfor the shaft to be part of the actuator. Finally, it is also possibleto couple a gas exchange valve, which is embodied as a through valve, tothe actuator using the connection according to the invention.

Other advantages and advantageous embodiments of the invention can beinferred from the following drawings, their description, and the claims.

DRAWINGS

FIG. 1 shows a full view of a first exemplary embodiment of a connectionaccording to the invention with the short shaft of the gas exchangevalve;

FIG. 2 shows a full view of a second exemplary embodiment of aconnection according to the invention with a through valve; and

FIGS. 3 to 6 show detailed views of various exemplary embodiments of theconnection according to the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows a gas exchange valve 1, which is coupled to an actuator 5by way of a connection 3. A control element 7 of the actuator 5 executesthe control movements that are to be transmitted to the gas exchangevalve 1 by way of the connection 3. Not shown in FIG. 1 is a valve seatin a cylinder head of the internal combustion engine, which is also notshown, against which valve seat a valve head 9 of the gas exchange valve1 rests when it is in the closed state. The connection 3 will bedescribed in greater detail below in conjunction with FIGS. 3 to 6.

FIG. 2 shows a gas exchange valve 1 that is embodied as a so-called“through valve,” which protrudes through the actuator 5 with its shaft11 and in which the control element 7 is disposed on the end of theactuator 5 oriented away from the valve head 9.

FIG. 3 shows a first exemplary embodiment of a connection 3 according tothe invention in a detailed exploded view. A coupling piece 13, which isconnected to the control element 7 of the actuator 5, is shown in FIG. 3in a partially sectional view. The coupling piece 13 has a cylindricalbore 15. In the bore 15, three beads 17 are provided spaced apart fromone another in the longitudinal direction of the bore 15.

There is an external thread 19 on the outer diameter of the couplingpiece 13. The coupling piece 13 has multiple slits in the longitudinaldirection. Only one slit 21 can be seen in FIG. 3. The slits 21 can beclearly seen in FIGS. 4 and 5.

A shaft 11 of a gas exchange valve 1 is shown below the coupling piece13. A number of circumferential grooves 25 are disposed at one end 23 ofthe shaft 11 oriented away from the valve head (not shown in FIG. 3).The dimensions and spacing of the circumferential grooves 25 apart fromone another correspond to the dimensions and spacing of the beads 17 inthe bore 15 of the coupling piece 13.

If the shaft 11 is now slid into the bore 15 from below, the couplingpiece 13 spreads open, which is easily possible because of the slits 21.As soon as the shaft 11 has reached a position in which the beads 17engage in detent fashion in the circumferential grooves 25, the couplingpiece 13 returns to its original shape and a positive engagement isproduced between the beads 17 of the coupling piece 13 and thecircumferential grooves 25 of the shaft 11. The circumferential grooves25 can have a semicircular, rectangular, or trapezoidal cross-section.It is also conceivable for the flanks of the circumferential grooves 25to enclose various angles with the longitudinal axis if, for example,the forces to be transmitted are different for opening and closing thegas exchange valve. It is also possible to provide the coupling piece 13on the gas exchange valve 1 and the circumferential grooves 25 on thecontrol element 7.

In order to prevent the positively engaging connection between thecoupling piece 13 and the shaft 11 from becoming detached duringoperation, after the shaft 11 is inserted into the bore 15, a nut 27 isscrewed onto the external thread 19 of the coupling piece and tightened.It is recommended that the external thread 19 and the nut 27 be embodiedwith a fine thread, so as to reliably prevent the nut 27 from comingloose. Naturally, any of the known screw locking devices can also beused to prevent the nut 27 from unintentionally coming loose.

Above the external thread 19 on the coupling piece 13, a recess 29 isprovided, which makes it easier for the coupling piece 13 to spreadopen.

FIG. 4 shows a second exemplary embodiment of a connection according tothe invention, likewise in an exploded view. The inner contour of thecoupling piece 13 corresponds to the inner contour of the coupling piece13 according to the exemplary embodiment shown in FIG. 3 and is notvisible in FIG. 4. The shaft 11 with multiple circumferential grooves 25spaced apart from one another is embodied exactly the same as explainedin the exemplary embodiment shown in FIG. 3.

The slits 21, which make it easier for the coupling piece 13 to spreadopen when the shaft 11 is inserted into the coupling piece 13, areclearly visible in FIG. 4. The number of the slits 21 can be selected asneeded.

Two grooves 31 are let into the outer circumference of the couplingpiece 13 according to the exemplary embodiment shown in FIG. 4. When theshaft 11 has been inserted into the coupling piece 13, two securingrings 33 are placed over the coupling piece 13 and inserted into thegrooves 31. The securing rings 33 can be embodied as open wire rings.The securing rings 33 are dimensioned and produced in such a way thatthey press the coupling piece together when they are placed in thegrooves 31. This simply and effectively prevents an undesired detachmentof the connection between the coupling piece 13 and the shaft 11.

FIG. 5 shows another exemplary embodiment of a connection according tothe invention between the coupling piece 13 and the shaft 11. Thecontour of the bore in the coupling piece 13, which is not visible, alsocorresponds to the contour of the bore 13 according to the exemplaryembodiment shown in FIG. 3 The coupling piece 13 is embodied in theshape of a cylinder in the vicinity of the slits 21. When the shaft 11is inserted into the coupling piece 13, a sleeve 35 is slid over thecoupling piece 13 in the vicinity of the slits 21. The sleeve 35 isshown in FIG. 5 in a partially sectional view. Once it is slid on, aforce fit is formed between the coupling piece 13 and the sleeve 35 suchthat the sleeve 35 fits snugly and securely on the coupling piece 13. Asan alternative, the sleeve 35 can be compressed onto the coupling piece13 after being slid into place.

FIG. 6 shows another exemplary embodiment of a connection according tothe invention. In this exemplary embodiment, the shaft 11 is slidthrough the control element 7 and the coupling piece 13 from beneath.The coupling piece 13 is shown in a partially sectional view. Thecoupling piece 13 spreads out in the vicinity of the beads 17 far enoughto permit the shaft 11 to freely slide through the bore 15 into itsinstallation position. Then the coupling piece 13 is pressed together sothat the beads 17 engage in detent fashion in the circumferentialgrooves 25, and a sleeve 35 can be slid onto it from above. A reliefgroove 37 is provided in the bore 15, which makes it easier for thecoupling piece 13 to spread out and be pressed together.

Naturally, all other types of securing elements, such as the securingrings 33 or the nut 27, for example, can also be used in the embodimentsof the coupling piece 13 in which the coupling piece is spread out. Noris the spreading out of the coupling piece 13 limited to the use ofthrough valves; it can also be used in a configuration according to FIG.1.

1-13. (canceled)
 14. A connection of a gas exchange valve of an internalcombustion engine to an actuator, the connector comprising a shaft (11)a coupling piece (13), at least one circumferential groove (25) on theshaft (11), the coupling piece (13) having a bore (15) whose diameterwhen assembled corresponds to the diameter of the shaft (11), the bore(15) having at least one circumferential bead (17), which can beconnected in a positively engaging manner to the at least onecircumferential groove (25), and the coupling piece (13) having at leastone slit (21) in the longitudinal direction of the coupling piece (13)in the vicinity of the bead (17).
 15. The connection according to claim14, wherein the shaft (11) comprises a number of circumferential grooves(25) spaced apart from one another in the longitudinal direction of theshaft (11), and the bore (15) comprises a number of beads (17) spacedapart from one another in the longitudinal direction.
 16. The connectionaccording to claim 14, wherein the shaft (11) is embodied in acylindrical shape in the vicinity of the at least one circumferentialgroove (25), and wherein the bore (15) is embodied in a cylindricalshape.
 17. The connection according to claim 15, wherein the shaft (11)is embodied in a cylindrical shape in the vicinity of the at least onecircumferential groove (25), and wherein the bore (15) is embodied in acylindrical shape.
 18. The connection according to claim 14, wherein theshaft (11) is embodied in the shape of a truncated cone in the vicinityof the at least one circumferential groove (25), and wherein the bore(15) is embodied in the shape of a truncated cone.
 19. The connectionaccording to claim 15, wherein the shaft (11) is embodied in the shapeof a truncated cone in the vicinity of the at least one circumferentialgroove (25), and wherein the bore (15) is embodied in the shape of atruncated cone.
 20. The connection according to claim 16, wherein theshaft (11) is embodied in the shape of a truncated cone in the vicinityof the at least one circumferential groove (25), and wherein the bore(15) is embodied in the shape of a truncated cone.
 21. The connectionaccording to claim 14, wherein the at least one circumferential groove(25) has a semi-circular, rectangular, or trapezoidal cross-section. 22.The connection according to claim 14, further comprising a securingelement, which prevents the connection from the shaft (11) and thecoupling piece (13) from becoming detached.
 23. The connection accordingto claim 15, further comprising a securing element, which prevents theconnection from the shaft (11) and the coupling piece (13) from becomingdetached.
 24. The connection according to claim 16, further comprising asecuring element, which prevents the connection from the shaft (11) andthe coupling piece (13) from becoming detached.
 25. The connectionaccording to claim 18, further comprising a securing element, whichprevents the connection from the shaft (11) and the coupling piece (13)from becoming detached.
 26. The connection according to claim 22,wherein the securing element is embodied as a wire ring (33) and whereinthe coupling piece (13) has at least one groove (31) on its outersurface to accommodate the wire ring (33).
 27. The connection accordingto claim 22, wherein the securing element is embodied as a nut (27) andwherein the coupling piece (13) has an external thread (19) thatcooperates with the nut (27).
 28. The connection according to claim 22,wherein the securing element (33) is embodied as a sleeve (35) andwherein the sleeve (35) can be slid over the coupling piece (13). 29.The connection according to claim 28, wherein the sleeve (35) and thecoupling piece (13) constitute a force fit when assembled.
 30. Theconnection according to claim 22, wherein the coupling piece (13) isspread open in the vicinity of the at least one bead (17) in comparisonto the assembled state, and wherein the coupling piece (13) is pressedtogether by the securing element (27, 33, 35).
 31. The connectionaccording to claim 29, wherein the coupling piece (13) is spread open inthe vicinity of the at least one bead (17) in comparison to theassembled state, and wherein the coupling piece (13) is pressed togetherby the securing element (27, 33, 35).
 32. The connection according toclaim 14, wherein the shaft (11) is part of the gas exchange valve (1)and wherein the coupling piece (13) is part of the actuator (5).
 33. Theconnection according to claim 14, wherein the coupling piece (13) ispart of the gas exchange valve (1) and wherein the shaft (11) is part ofthe actuator (5).